Sub Bass Frequencies and Acoustic Instruments

The sound and esthetics of current film and game music has led to a common misconception with inexperienced composers and orchestrators about what is possible to expect when working with acoustic instruments. Particularly the bass register is often overestimated and leads to orchestration decisions that are rather counter productive.

Hearing low booms and sub bass punches paired with acoustical substantial sustaining low drones in scores often leads to the belief that the sources of these sounds can be found in the orchestra. Of course, many people are aware of synths and additional percussion layers that might be used but often overlook common techniques that are used to enhance the bottom end of these sounds like layered sub bass synths etc.

The general thing to understand here is that the sub bass range is practically impossible to create with substance on acoustical instruments. There might be  a short peak of it with bass drum hits or the rare case of very large pipe organs but generally, without help acoustic instruments  are not capable of providing this frequency range at considerable volumes.

However, I very often see attempts to orchestrate these frequencies which in most cases lead to the completely opposite effect than desired:

The overuse of the lowest string on the double basses will not create any considerable "sub bass" feeling. In fact the acoustic dimensions of the bass rather favour frequencies an octave higher which carry and resonate way more. The lowest string povides a rather weak, unfocussed and "flabby" sound that by no means has a lot of substantial carrying power. This range should rather be saved for moments when you are looking for a rather "black" and dark sound, not a bassy fundament.

Same applies for low trombones and tuba: The lowest notes are extremely tricky to produce, compromised in sound quality and of little carrying power. Concentrating your orchestrations in this register will create a rather weak and by no means brassy and powerful impression. With all these low registers on any instrument you should be aware that the attack time will become considerably longer so it is more or less impossible to expect punchy and stabby attacks in these ranges.

One more candidate for too low and consequentially ineffective scoring are the timpanis. The theoretical range ends at the c two octaves below middle c but particularly the lowest few notes are quite problematic in sound as the skin of the timpani will need to be relaxed quite alot to resonate at these tones which however causes it to be rather unfocussed and losing any punch. 

In most of the above described cases, the octave higher will be the better choice as it either creates more carrying power or more punch.

The creation of sub bass frequencies should be left to additional synth sounds that you either layer to support acoustic instruments or use as individual and identifiable elements and additional colour. Yet, I would advise not to overuse these as it weakens their effect. Usually having a sub bass synth join on a pivotal moment has a way stronger effect than using it all the way through.

There are also other ways to create sub bass frequencies, for instance octavers that generate an additional lower octave out of its input source materials. They however sound different and vary in substance based on their input signal so there is no better or worse way but just different creative approaches.

One really bad way however is to try to boost sub bass frequencies with an EQ on acoustic instruments as you cannot boost anything that is not there. So if you boost that range the only thing you will boost is noticeable noise that has no benefit whatsoever.

However, very often the perceived effect of "lots of bass" lays higher in the frequency range than you might imagine so boosting frequencies between 70-100Hz might actually create a perceived boost in bass.

Which way to go is depending on genre or taste but the bottom line here should be that you should not sacrifice idiomatic writing for the prospect of adding sub bass material with acoustic instruments as this is practically not possible.